The Fornax and Eridanus Clusters

The Fornax and Eridanus clusters are two very famous clusters in the
southern hemisphere. Although they look near to each other, they are separated
by about 20 million light years. The nearer Fornax cluster is about 65 million
light years from us, and the Eridanus cluster is about 85 million light years
from us. There are many other groups of galaxies scattered around these two
clusters and collectively these groups are often called the Fornax Supercluster or
Southern Supercluster.

The Fornax Cluster

This is a map of the Fornax Cluster. This is the most famous of the two
clusters because it has a compact core of galaxies scattered across two
degrees of the sky which makes it a popular target for amateur astronomers.
This cluster contains two huge galaxies - NGC 1316 and NGC 1365 - which are
larger than any of the galaxies in the Virgo cluster.

Below - the two largest galaxies in the Fornax cluster. NGC 1316 (left)
is a massive lenticular galaxy - the faint signs of spiral structure in this
galaxy may indicate that it has recently swallowed a spiral galaxy. NGC 1316
is a powerful radio source (it is known as Fornax A by radio astronomers).
Visible above the galaxy is NGC 1317 - a spiral galaxy which may become
another victim of this huge galactic cannibal. NGC 1365 (right) is the most
famous galaxy in the Fornax cluster. It is a barred spiral galaxy with a
beautiful shape.

NGC 1316

NGC 1365

This is a list of the main galaxies in the Fornax cluster. These are the
54 largest galaxies in this cluster. This is about one third of the number
of comparable galaxies in the Virgo cluster.

Column 1: The usual name of the galaxy.
Column 2: The Right Ascension for epoch 2000.
Column 3: The Declination for epoch 2000.
Column 4: The blue apparent magnitude of the galaxy.
Column 5: The galaxy type: E=Elliptical, S0=Lenticular, Sa,Sb,Sc,Sd=Spiral,
SBa,SBb,SBc,SBd=Barred Spiral, Sm,SBm,Irr=Irregular.
Column 6: The angular diameter of the galaxy (arcminutes).
Column 7: The diameter of the galaxy (thousands of light years).
Column 8: The recessional velocity (km/s) of the galaxy relative to
the cosmic microwave background.
References:
The HyperLeda Database, (2003).

Below - three more galaxies in the Fornax cluster. NGC 1350 (left) is
large barred spiral galaxy. NGC 1399 (centre) is the large elliptical galaxy
at the heart of the cluster. NGC 1404 (right) is another large elliptical
galaxy near NGC 1399.

NGC 1350

NGC 1399

NGC 1404

Shown below is a picture of the middle of the Fornax Cluster. The cluster
has a compact core containing a lot of bright galaxies which means that it
actually looks better on a photograph than the Virgo cluster. The bright
elliptical galaxy in the centre is NGC 1399, and the famous barred-spiral
galaxy NGC 1365 can be seen at the bottom-right corner.

The middle of the Fornax cluster. Image size 2.0°x1.6°. DSS image.

Properties of the Fornax Cluster

Equatorial Coordinates

RA=03h35m Dec=-36°

Galactic Coordinates

l=238° b=-54°

Supergalactic Coordinates

L=262° B=-41°

Distance to the centre of the cluster

65 million light years

Number of large galaxies in the cluster

54

Alternative names for the cluster

Fornax I cluster

The Eridanus Cluster

This is a map of the Eridanus Cluster. This cluster is less spectacular
than the Fornax cluster, partly because the galaxies are spread across a
larger area and partly because the cluster is rather further and hence dimmer
than the Fornax cluster. The Eridanus cluster is roughly split into two
halves: a northern subgroup around NGC 1407 and a southern subgroup around
NGC 1395.

Below - three spiral galaxies in the Eridanus cluster. NGC 1300 is a large
barred spiral galaxy. NGC 1371 (centre) and NGC 1385 (right) are two spiral
galaxies to the south of the centre of the cluster and probably close
companions.

NGC 1300

NGC 1371

NGC 1385

This is a list of the 73 largest galaxies in the Eridanus cluster. This
is a longer list than that for the Fornax cluster. The Eridanus cluster seems
to be the slightly larger and the slightly richer of the two clusters.

Column 1: The usual name of the galaxy.
Column 2: The Right Ascension for epoch 2000.
Column 3: The Declination for epoch 2000.
Column 4: The blue apparent magnitude of the galaxy.
Column 5: The galaxy type: E=Elliptical, S0=Lenticular, Sa,Sb,Sc,Sd=Spiral,
SBa,SBb,SBc,SBd=Barred Spiral, Sm,SBm,Irr=Irregular.
Column 6: The angular diameter of the galaxy (arcminutes).
Column 7: The diameter of the galaxy (thousands of light years).
Column 8: The recessional velocity (km/s) of the galaxy relative to
the cosmic microwave background.
References:
The HyperLeda Database, (2003).

Below - three more galaxies in the Eridanus cluster. NGC 1395 (left) is
the largest elliptical galaxy in the southern half of the cluster. NGC 1398
(centre) is a large spiral galaxy at the southern edge of the cluster.
NGC 1407 (right) is the largest elliptical galaxy in the northern half of the
cluster.

NGC 1395

NGC 1398

NGC 1407

Shown below is NGC 1232. Located to the right of the cluster, this is
another of the many spiral galaxies located in this group. This is one
the most beautiful galaxies in the cluster because of its multiple spiral
arms.